The present invention relates to a cylindrical battery.
Main batteries which are put to practical use at present include lead acid battery, nickel-cadmium battery, nickel-metal hydride battery, silver oxide-zinc battery, and lithium ion battery.
A lead acid battery comprises lead dioxide as a positive active material, lead as a negative active material and dilute sulfuric acid as an electrolyte and has an operating voltage of about 2 V. This battery has well-balanced quality, reliability and price and finds wide application for use in automobile, electric vehicle, uniterruptible power supply, etc. With the recent technique for the reduction of the size of battery and sealing the battery, this battery has been used more and more for various cordless apparatus.
A nickel-cadmium battery comprises nickel oxyhydroxide as a positive active material, cadmium as a negative active material and an aqueous solution of potassium hydroxide as an electrolyte and has an operating voltage of about 1.2 V. This battery has a small internal resistivity, can be discharged with a large amount of current, a prolonged cycle life and a wide working temperature range and is resistant to overcharging/overdischarging. Therefore, this battery has been widely used mainly for consumers"" apparatus.
A nickel-metal hydride battery comprises nickel oxyhydroxide as a positive active material, a hydrogen-storage alloy as a negative active material and an aqueous solution of potassium hydroxide as an electrolyte and has an operating voltage of about 1.2 V. This battery also has a high energy density and thus has been practically used mainly for various consumers"" apparatus.
A silver oxide-zinc battery comprises silver oxide as a positive active material, zinc as a negative active material and potassium hydroxide aqueous solution as an electrolyte. This battery has a high output and a high energy density but is expensive. Therefore, a large-sized silver oxide-zinc battery is used mainly for space and deep sea while a small-sized silver oxide-zinc battery has been widely used for watch and desktop electronic calculator.
A lithium ion battery comprises a Li-metal composite oxide such as LiCoO2, LiNiO2 and LiMn2O4 as a positive active material, a carbonaceous material as a negative active material and an organic solution as an electrolyte and has an operating voltage of 3 V level. Because of its advantages such as high operating voltage, high energy density and no memory effect, this battery finds rapidly growing application for consumers"" use.
The foregoing practical batteries are provided in the form of rectangle, cylinder, button, sheet, etc. depending on the purpose.
As well known, a cylindrical battery comprises a plate group obtained by spirally winding a thin positive electrode plate and a thin negative electrode plate with a separator interposed therebetween received in a closed-end cylindrical battery container. Because of capability of being rapidly charged, this type of battery has faced a growing demand for various purposes.
Cylindrical batteries can be roughly divided into two groups, i.e., structure comprising a closed-end cylindrical metallic battery container as a battery jar and structure comprising a closed-end cylindrical resinous battery container as a battery jar. In the case of the latter structure, a cylindrical battery main body comprising a resinous closed-end cylindrical battery jar may be received in a closed-end metallic container.
In the case where the cylindrical battery is used in such an arrangement that a cylindrical battery main body comprising a resinous closed-end cylindrical battery jar is received in a closed-end metallic container, the conventional form of such a type of cylindrical battery normally comprises a spirally-wound plate group 2 having two output terminals 1a, 1b on the same edge face thereof, a resinous closed-end cylindrical battery jar 3 for receiving the spirally-wound plate group 2, and a cover 4 as shown in FIG. 1. The output terminals 1a and 1b connected to the positive electrode and negative electrode of the spirally-wound plate group 2, respectively, are drawn out of the battery jar through two ports formed in the cover 4, respectively. A cylindrical battery main body 5 is received in the metallic container with the bottom 6 of the battery jar positioned at the same side to the bottom 8 of the metallic container 7. The edge of the metallic container 7 on the opening side thereof is bent toward the cover 4 of the cylindrical battery main body 5 to form a bent portion 9.
However, this structure is disadvantageous in that the cover 4 of the cylindrical battery main body 5 is positioned on the opening side of the metallic container 7 and thus is vulnerable to impact (e.g. falling) possibly resulting in the leakage of electrolyte through the connection between the battery jar 3 and the cover 4.
A countermeasure against the foregoing problem, if any, is to increase the thickness of the cover 4 or the battery jar 3 or increase the size of the bent portion 9 of the battery container 7. However, this countermeasure is disadvantageous in that it adds to the weight of the battery or reduces the energy density of the battery.
It is therefore an object of the invention to provide a cylindrical battery which exhibits an improved impact resistance without deteriorating the specific energy or energy density.
The foregoing object of the present invention will become apparent from the following detailed description and examples.
The first aspect of the present invention lies in a cylindrical battery comprising a cylindrical battery main body 5 received in a closed-end cylindrical metallic container 7, wherein said cylindrical battery main body 5 comprises a spirally-wound plate group 2 having two output terminals 1a, 1b on the same edge face, a closed-end cylindrical resinous battery jar 103 for receiving said spirally-wound plate group 2 and a resin cover 104 for closing the opening of said battery jar 103, said two output terminals 1a, 1b extend to the exterior of said battery jar through two ports formed on the bottom 106 of said battery jar, respectively, and said cylindrical battery main body 5 is received in said metallic container 7 with said cover 104 disposed at the bottom 8 of said metallic container 7.
The second aspect of the present invention lies in the foregoing cylindrical battery, wherein the cylindrical battery is a secondary battery.
The third aspect of the present invention lies in the foregoing cylindrical battery, wherein the cylindrical battery main body 5 is received in said metallic container 7 and the edge 9 of said metallic container on the opening side thereof is bent toward said cylindrical battery main body 5.
The fourth aspect of the present invention lies in the foregoing cylindrical battery, wherein the battery jar 103 and cover 104 comprise a polyolefin resin and the metallic container 7 comprises aluminum.
The fifth aspect of the present invention lies in the foregoing cylindrical battery, wherein the spirally-wound plate group 2 comprises a positive electrode comprising lead dioxide as an active material and a negative electrode comprising lead as an active material.